ADC circuits are useful in many applications where it may be desirable to quantize an analog input signal into a digital output signal. A variety of ADC architectures have been employed in conventional architectures including flash converters, folding converters, sub-ranging converters, multi-step converters, pipeline converters and successive approximation converters. In some system, multiple ADC circuits are used so that multiple analog signals can be captured at the same time.
One example application of multiple ADC circuits is a multi-channel oscilloscope, where one ADC circuit is used for each individual channel of the oscilloscope. For this example application, data from each channel of the oscilloscope is represented as a separate waveform on the display. Therefore, the timing relationship between each ADC in the multi-channel oscilloscope needs to be known so that the waveforms can be aligned with one another on the display.
In another example application of multiple ADC circuits, a phase-array antenna system includes a multiplicity of antenna elements arranged in an array. Each of the antenna elements includes a receiver circuit. Data from each element of the antenna array can be utilized in such a way as to identify the difference in relative phases of the signals from each antenna element, and thus the selective use of the antenna elements can be used to synthetically steer the beam of the antenna in a desired direction, while suppressing undesired directions. The output of each of the receiver circuits can be processed by ADC circuits. Since the phase and timing information of the antenna array are critical, the timing relationship between the ADC circuits need to be known to properly synthesize the aperture and direction for the beam of the antenna.